Impact of climate changes on the incidence of tick-borne encephalitis in the Czech Republic in 1982–2011
Authors:
B. Kříž 1,2; I. Kott 3; M. Daniel 1; T. Vráblík 3; Č. Beneš 1
Authors‘ workplace:
Státní zdravotní ústav, Praha
1; Univerzita Karlova, 3. lékařská fakulta
2; Český hydrometeorologický ústav
3
Published in:
Epidemiol. Mikrobiol. Imunol. 64, 2015, č. 1, s. 24-32
Category:
Review articles, original papers, case report
Overview
Study objective:
To analyse the impact of climate changes on the increase in human cases of tick-borne encephalitis (TBE) in three high-incidence regions of the Czech Republic over the period 1982 to 2011.
Material and methods:
Data on TBE cases were derived from the national reporting system EPIDAT. TBE is a reportable infectious disease in the Czech Republic. This study analysed data on TBE cases from three high-incidence regions that vary relatively widely in the average altitude and biotope types. The meteorological data for the study period, obtained from 26 stations of the Czech Hydrometeorological Institute (CHMI) which make standard meteorological measurements, were checked for correctness. The average altitude was determined for each study region. The STATISTICA 6 software was used for the basic statistical analysis (lit.). Pearson’s correlation coefficient was used to assess the strength of the relationship between the variables and the 5% level was set as the criterion of statistical significance. The impact of the time lag between the epidemiological and meteorological quantities was also tested.
Results:
The impact of the meteorological quantities temperature and precipitation rate on the occurrence of 6,229 TBE cases in three administrative regions varying in biotopes, altitude, and epidemiological characteristics of TBE infection was assessed. When evaluating the 30-year period 1982–2011 year by year in three regions, a significant correlation was found between TBE onset and average air temperature in 100%, 90%, and 80% of years, with 11-20-day intervals to the onset of the disease. A significant correlation between the incidence of TBE cases and the precipitation rate was observed for 40%, 43%, and 40% of years. When considering the summary results for the overall study period divided into three seasons (March-April, May-June, July-November), a significant correlation was identified between TBE incidence and temperature in all three seasons, with 0-30-day intervals to the onset, in all three regions.
When considering the relationships between TBE incidence, air temperature, and precipitation rate for the overall study period divided into three seasons (March-April, May-June, July-November), a significant correlation was identified between TBE incidence and temperature in all three regions. A correlation between TBE incidence and precipitation rate was only found for the period May-November.
Moreover, the impact of air temperature and precipitation rate in the second half of the previous year on TBE incidence in the first half of the following year was tested. A positive correlation between air temperature and TBE incidence in the first half of the following year was found in three regions for 79.3%, 62.1%, and 48.3% of years of the study period. A positive correlation between precipitation rate and TBE incidence was only found in these regions for 3.4%, 17.2%, and 6.9% of years of the study period.
Conclusions:
From the study results, it follows that air temperature had a major impact on TBE incidence in the regions studied. A correlation between TBE incidence and precipitation rate was found clearly less often, mostly in summer and autumn months. Air temperature and precipitation rate in the second half of the previous year did not have a major impact on TBE incidence in the first half of the following year.
Keywords:
tick-borne encephalitis – incidence – climate impacts – temperature – precipitation
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Hygiene and epidemiology Medical virology Clinical microbiologyArticle was published in
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